[Date Prev][Date Next]
Re: performance very differently for two hosts that are configured identical
I found the problem. Stupid problem, this took us several days!
Since it has been so many days, I quote the full original question for
your reference, see the bottom for the last jigsaw of the puzzle
Zhang Weiwu wrote:
> We have a development server 'emerson' with roughly one third of the
> performance of our productional server 'bossdog', it runs ldap query 10
> times faster than the productional server. I checked everything I can to
> find out the difference, it seems both are equally configured.
> Test method:
> emerson:~# time for (( i=0; i<100; i++)); do ldapsearch -xD cn=manager,dc=eoa,dc=cn -w masked -b ou=contacts,ou=realss.com,dc=eoa,dc=cn '(uidNumber=7)' dn; done;
> # zhangweiwu, contacts, realss.com, eoa.cn
> dn: uid=zhangweiwu,ou=contacts,ou=realss.com,dc=eoa,dc=cn
> # search result
> search: 2
> result: 0 Success
> # numResponses: 2
> # numEntries: 1
> real 0m1.047s
> user 0m0.320s
> sys 0m0.352s
> bossdog:~# time for (( i=0; i<100; i++)); do ldapsearch -xD cn=manager,dc=eoa,dc=cn -w masked -b ou=contacts,ou=realss.com,dc=eoa,dc=cn '(uidNumber=7)' dn; done;
> real 0m41.790s
> user 0m0.232s
> sys 0m0.464s
> What I have compared:
> 1. Both server uses Debian Lenney
> 2. Both server have same DB_CONFIG in /var/lib/ldap
> 3. Both server have same ACL settings. In fact we tried to reduce the
> ACL setting on the slow preforming productional server without
> improvement result.
> 4. Both server uses bdb
> 5. Compare syslog at log level 256 both server produce same log messages
> 6. The productional server shows harddisk is twice as fast as
> development server (hdparm), free memory more than the development
> server, and its dual-core xeon cpu should outperform the VIA CPU
> used in the development server, yet slower. The productional
> server average load is 0.5 which is not high for dual-CPU (with
> hyperthreading display as 4 CPUs to Linux).
> 7. Productional server DB is then re-built (by rm -rf & slapadd)
> without noticeable change in performance.
> This performance difference resulted the productional server user
> interface much slower than user's patience.
> What would you check further in this case? Thanks in advance
The problem is we have been looking into openldap and system
resource/kernel so much that we forgot other software directly related
to performance. There had been something wrong made syslog low
performance, change loglevel to none instantly solves the problem.